Dispatchers received reports of the non-injury blaze about 7:40 a.m. at a two-story building on La Mesa Boulevard, just north of Grossmont Boulevard, Heartland Fire and Rescue spokesman Sonny Saghera said.

Firefighters responded to the scene and saw light smoke coming from the building, then made their way inside and located the fire in one suite on the first floor of the building, Saghera said.

Crews contained the blaze to that one suite and knocked down the flames within five minutes, he said, adding that the suite sustained moderate smoke damage.

Investigators believe the cause of the fire was a faulty light and pump on a fish tank, Saghera said. Fish inside the 40-gallon tank were killed.